1. Field of the Invention
The present invention relates to an apparatus for penetrating body tissue. More particularly, the present invention relates to a trocar assembly having an electrical tissue penetration indicator.
2. Description of the Related Art
Endoscopic surgical procedures, that is, surgical procedures performed through tubular sleeves or cannulas, have been utilized for many years. Initially, endoscopic surgical procedures were primarily diagnostic in nature. More recently as endoscopic technology has advanced, surgeons are performing increasingly complex and innovative endoscopic surgical procedures. In endoscopic procedures, surgery is performed in any hollow viscus of the body through a small incision or through narrow endoscopic tubes either (or cannulas) inserted through small entrance wounds in the skin. In laparoscopic procedures surgery is performed in the interior of the abdomen.
Laparoscopic procedures generally require that any instrumentation inserted into the body be sealed, i.e., provisions must be made to ensure that gases do not enter or exit the body through the laparoscopic or endoscopic incision as, for example, in surgical procedures in which the surgical region is insufflated. Moreover, laparoscopic and endoscopic procedures often require the surgeon to act on organs, tissues and vessels far removed from the incision, thereby requiring that any instruments to be used in such procedures be both long and narrow.
Typically, after the surgical region is insufflated, trocars are used to puncture the body cavity and provide the above noted cannula used during endoscopic procedures. Generally, trocars used during such procedures include a styler having a sharp tip for penetrating the body cavity positioned coaxially within protective tubes to protect a patient or surgeon from inadvertent contact with the tip. An example of a known trocar is described in commonly assigned, U.S. Pat. No. 4,601,710 to Moll. Most currently used trocars rely on protective tubes to prevent inadvertent contact with the tip, which utilize intricate mechanical designs to achieve the desired protective feature.
Another type of trocar used for penetrating body tissue is described in European Patent Application No. 0 484 725. That trocar has a hollow shaft and a tip at a distal end portion of the hollow shaft formed as a window made from a suitable transparent material, such as glass quartz or glass plexiglass. An optic guide and a fiber optic lighting unit are fed to the tip through the hollow shaft. Typically, the optic includes fiber optic light guides which are fed through the hollow shaft to the tip. The optic ends at an axial distance behind the vertex point of the tip so that the optic illuminates the entire lateral surface of the conical window for observation purposes. In this configuration, the operator has an interior view of the structures that will be penetrated when inserting the instrument. Thus, the operator can, for example, detect blood vessels before they are encountered by the tip of the instrument and avoid them. More particularly, the operator can observe the distal end of the tip when penetrating the peritoneum and after complete penetration so that the subjacent vessels and structures of the peritoneum are avoided.
The present invention provides a new and different apparatus and method for detecting penetration of the peritoneum or other body portions with a trocar assembly.